Elongated wedge-type devices for retaining printed circuit boards (“PCBs”) within elongated slots in racks or chassis are in common use. The devices typically include a center wedge having sloped surfaces at opposite ends and two end pieces having sloped surfaces that abut against the sloped surfaces of the center wedge. The retaining devices are typically constructed with three or five wedges. A screw or shaft extends lengthwise through and connects the end wedges and the center wedge. In operation, a PCB is typically fastened to the backside of the center wedge. The PCB, with the retaining device attached thereto, is placed within the desired slot of the rack. Rotating the screw or shaft in one direction draws the two end wedges toward each other, causing them to deflect transversely on the sloped abutting surfaces of the center wedge. This results in increasing the device's effective width and wedging the PCB into the desired location. Rotating the screw in the opposite direction moves the two end wedges apart from each other bringing them back into longitudinal alignment with the center wedge and, thereby, releasing the PCB. Examples of such devices are described in greater detail in U.S. Pat. Nos. 4,775,260, 5,607,273, and 5,779,388, which are hereby incorporated by reference.
PCB retaining devices are preferably designed to limit the amount of force applied to the PCB while held in a slot. One solution to this problem has been to integrate clutch assemblies into the retaining device. The clutch is typically configured to have a first and second clutch head having cooperating teeth. By manipulating the angle of the clutch head teeth and the force in which the clutch heads are urged together, the torque applied to the screw and, in turn, the wedging force generated by the retaining device may be controlled. Unfortunately, the integration of the clutch assembly into the retaining device has typically led to the use of custom components in the retaining device. Utilization of custom components results in increased design and manufacturing costs and limits the number of suppliers from which the components can be sourced. It would be desirable to develop a PCB retaining device that maximizes the use of off-the-shelf parts without sacrificing utility. If custom components are used, it would be desirable to limit them to small, relatively affordable components.